Heated bed 2500 Watt + Duet3 6hc

dutti

Hey,
How can I correctly connect the Duet3 6hc with a solid state relay (25a I have heer) with my Duet3?
Would be Nice if anyone has a good and safe solution. Thanks

Phaedrux

Can you give more specifics and details?

Connecting an AC bed heater via SSR is quite straight forward. You connect the SSR input to the normal bed terminals and wire the bed and ac power accordingly.

dc42

@barbarossa-cologne, have you read https://duet3d.dozuki.com/Wiki/Choosing_a_bed_heater#Section_Bed_heater_driven_using_a_Solid_State_Relay ?

dutti

@dc42 yes, but for me it's not easy. It's my first project. Like I understood I have to connect the state relay between the mainboard and the heated bed. But I'm not pretty sure how to wire this exactly.

dutti

@Phaedrux what details do you need exactly?
Power supply?

Phaedrux

Does a diagram help?

https://forum.duet3d.com/assets/uploads/files/1565106228661-xyyknu7.jpg

What type of SSR is it?
What is the heated bed?
What is your PSU?
How do you have things wired currently if at all?

dutti

@Phaedrux
SSR: Type: ZG3NC-240B
Input: 3-32VDC
Output: 40A 30-240VAC

Silicon Heater: 85x85cm - 2500watt

RSU: Meanwell SNT HRP 600 24: 640 W, 24 V, 27 A

I havent wired yet. I´m a bit scared to destroy the expansiv mainboard.
Thanks for the help.!

dutti

@Phaedrux the diagramm is very good!!
the only thing I´m confused about is the power switch beetween RSU and the electronic. Is it also possible to have the power switch between socket and RSU?
Where Do I have to connect the cable in the Duet3? At the 15a high current in and output?
thanks

Phaedrux

https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Wiring_Diagram

Yes Out0 would be the normal candidate for the bed heater due to it's 15a capacity, but since you're using an SSR you could use any of the output pins to drive it.

https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Hardware_Overview#Section_Heating_Fans

dutti

@Phaedrux RSU has 27a and the SSR40a. Is this a problem?'
Or must be the current of the SSR less than the RSU..?
thanks

Phaedrux

The SSR rating is just for it's max capacity, not what it draws or anything like that.

What are the specs of your heater?

dutti

@Phaedrux 85x85cm silicon heater
2500watt

Phaedrux

What is your regional ac voltage? 110 or 220?

110 would be ~22a current
220 would be ~11a

theruttmeister

@barbarossa-cologne

I think you mean PSU,

The PSU has a rating for the amount of power it can supply. The SSR is just a switch, but its rating is like a wire, how much current it can carry.

The PSU and SSR are doing separate things, they just happen to use the same measurements (Amps).

Your bed heater will draw ~11 amps (I'm assuming you are in Europe based on your username) with the 220V from the wall, the SSR can carry a lot more (which is good, because the rating on SSR's is often over optimistic) (@Phaedrux I think got those numbers reversed).

The PSU can supply 27 amps, but that is at the 24 volts its putting out, its not being used to power the heater.

One thing to keep in mind, if you do something crazy, like max out the PSU by using it to drive an extra heater or a heated chamber... The combined power requirement would be over 3000 watts.
That would be more than is safe on a normal European wall plug (they are normally 13A max).

dutti

@theruttmeister
yes, of course PSU. sry
Rigth. I´m in cologne. So it´s 220v.
So when I understand it rigth, I should buy a second power supply with more volts for connecting the SSR and the heater?

thanks for the explanation

Phaedrux

@theruttmeister said in Heated bed 2500 Watt + Duet3 6hc:

@Phaedrux I think got those numbers reversed).

Yup I did, sorry.

dc42

@barbarossa-cologne said in Heated bed 2500 Watt + Duet3 6hc:

@theruttmeister
yes, of course PSU. sry
Rigth. I´m in cologne. So it´s 220v.
So when I understand it rigth, I should buy a second power supply with more volts for connecting the SSR and the heater?

Is it a 220V AC bed heater? If it is, then you don't need a PSU for it. If it isn't, then you have the wrong SSR and we need to know what voltage it is.

Tom Sanladerer posted a video on using SSRs to control AC mains bed heaters here https://www.youtube.com/watch?v=TiEwNf1H_Tc.

dutti

This post is deleted!

dutti

correct?

theruttmeister

@barbarossa-cologne

An SSR is just a switch. The control side only needs to be 24V (actually anything from 3-48V is common, the SSR will be marked), the PSU is powering just the switching of the SSR, which uses a very small amount of power.
The whole point of using an SSR is that the other side of the switch can be for much higher voltages and can carry lots of current.

So your wall socket can supply up to 13A, your SSR can carry 25A and the bed only draws 11A. Everything is good.

The PSU is not powering the bed in any way at all. Its just controlling the switch.